Who gets it, and what usually lies behind itEmerging evidence
In the one study of professional road riders (109 riders), 58% had had low back pain in the past year. In 1,274 Italian amateurs, 26.5% had it in the past year, and among 1,521 riders who went to bike-fit services, 29.2% reported it, slightly more often in mountain bikers, younger riders and heavier riders. It is usually ordinary low back pain, often a strained muscle or with no clear cause, and the National Health Service (NHS) says it usually improves within a few weeks.
These are associations from surveys, not proof of cause. A past bout of back pain went with about 4 times the odds; riding 160 kilometres (about 100 miles) or more a week went with 3.6 times the odds in 66 club riders; and coached or planned training went with about half the odds. In 40 men, a 3-hour ride raised back pain by the same amount on a road bike and a mountain bike, which the authors put down to the rider more than the bike.
Sources 1, 2, 3, 4, 5, 6
Why the riding position mattersEmerging evidence
In reviews of small studies, lower handlebars went with more rounding at the base of the spine, and a lower, further grip went with more rounding of the lower back (16 studies). Riders whose back pain comes on with a rounded position sat more rounded throughout a 2-hour outdoor ride, and their pain rose. Off-road racers with back pain had thinner deep trunk muscles and less back endurance, with no difference in strength or flexibility.
These are small studies and associations. One older lab study found lower bars didn't change the lower back's curve, and in static photos, body position didn't separate riders with and without back pain. Our reading: a long time bent and stretched forward, with back muscles that tire, is the most consistent pattern.
Sources 7, 8, 9, 10, 11, 12, 13, 14
Does cycling harm the back? It seems notEmerging evidence
In 18 high-volume road riders against 18 non-sporting adults, the riders' discs looked better hydrated on magnetic resonance imaging (MRI), their deep hip flexor muscles were bigger and their trunk endurance was better. That was a one-time comparison, not proof.
In 64 adults with long-lasting back pain, 8 weeks of stationary cycling or specific trunk exercises both reduced pain. Trunk exercise did better for disability at 8 weeks, but the groups didn't differ by 6 months.
Sources 15, 16
Saddle numbness, and the emergency signsEmerging evidence
The NHS lists loss of feeling or numbness around the genitals or bottom, new trouble peeing or controlling your bladder or bowels, changes in sexual sensation or function, and pain, tingling, weakness or numbness in both legs as signs of cauda equina syndrome: call 999 or go to accident and emergency (A&E).
Riders also get numbness from saddle pressure. Women who rode had 6.5 to 9.1 times the odds of genital numbness of women who swam or ran. In men, standing for more than a fifth of the ride and bars level with or above the saddle went with less numbness, and in healthy men, saddles without a nose and recumbent bikes lowered pressure on the area. A review suggests standing on the pedals every 10 minutes or so, on indirect evidence.
Our suggestion: numbness that clears soon after a ride, with none of the emergency signs, is usually saddle pressure; numbness that doesn't clear needs checking urgently.
Sources 6, 17, 18, 19, 20
When a scan helpsStrong evidence
The National Institute for Health and Care Excellence (NICE) advises against routine imaging for low back pain, and in specialist care only when the result would change what's done. Scans of people without back pain often show disc degeneration (37% at 20, rising to 96% at 80) and bulges, so a report can mislead. The warning signs are the exception.
Sources 21, 22
How it usually goesStrong evidence
Across 33 studies that followed people with new back pain, average pain fell from 52 out of 100 to 23 at 6 weeks, 12 at 6 months and 6 at a year. It often comes back: in a trial's comparison group, half had another bout that limited their activity within 112 days. No study has followed riders, and no one can promise a date.
Sources 23, 24